The present invention relates to impact grinders, hammermills or the like, and in particular, to hammermills for grinding corn and similar friable material.
Typical hammermills for grinding friable material such as corn or the like, impact the material with rotating hammers and control particle size by the opening size of a screen against which the hammers force the material. Throughput rate and hammer-to-screen clearance have an effect on hammermill efficiency. It is commonly accepted that for a given product such as shelled corn, an optimum hammer tip speed of, for example, 17,000 feet per minute (f/m) must be achieved for the most efficient operation. Most commercially available hammermills represent a compromise in tip speed in order to grind different products reasonably well.
In the article, "Increasing Hammermill Efficiency: A Need in an Era of Rising Power Costs", published in December 1981 by the Sprout-Waldron Division of Koppers Company, Inc. the present inventor describes the operation of a conventional hammermill for grain processing, whereby the material is ultimately forced through screen perforations by the action of the rotating hammers. The cost for manufacture of the screen component of a hammermill, and the need for frequent replacement of the screen, represent a significant initial and ongoing financial outlay.